On a side note, I have a wood stove and one of the big lessons that I have learned with burning in the stove is that smaller is better!!! I like the length of my rounds to be about a 12 inches, and I like each piece to be no thicker then 6 inches at the bark. It burns so clean and efficiently that during the coldest nights when it gets into the teens, we can heat the house with one load of wood that one of us brings in.
I made the mistake of cutting my rounds to 18 inches when I first had it and that was just terrible. Harder to get the fire going and tougher to handle. I also found that my 27 ton log splitter cuts through anything that's 12 inches long without effort, but there are some 18 inch rounds that it would struggle with. Then there is the fact that they are just a lot heavier and more difficult to get onto the splitter. I absolutely hate splitting wood with the splitter in the up/down position, so keeping those rounds to 12 inches makes it easy to handle while splitting in a comfortable standing position.
For storing and stacking, they seem to stack tighter at 12 inches.
Eddie